祁连山豆科植物根瘤内生细菌多样性及形成机制

The establishment of nitrogen-fixing symbiosis with some soil bacteria, collectively called rhizobia, is a unique feature of the plants of the legume family (Leguminosae or Fabaceae). Traditionally, rhizobia are included in the well-known genera Rhizobium, Bradyrhizobium, Sinorhizobium, Mesorhizobium, Azorhizobium and Allorhizobium of Alphaproteobacteria. Recently，some research reports showed varied endophytic bacteria in the root nodules of some legumes，which attracts great interest in research field of rhizobia． Because of antimicrobial activity and plant growth-promoting effect, endophytic bacteria become an important source of biocontrol agents and new drugs for human, plants and animals disease treatment. Taking two dominant legumes at different elevations of Qilian Mountain as raw meterials, the diversity of endophytic bacteia inside rhizobia isolated were investigated, and the mechanism between the endophytic bacteia and rhizobia were discussed in this topic. A series of polyphasic taxonomy technologies were used to determine the phylogeny and the calssification of endophytic bacteria inside rhizobia. Combination the results of PCA, CCA and RDA analyses of ecosystem, the relationship between diversity and elevation was illustrated. Use nodulation test with AFP mark and symbiotic genes, clarify the way endophytic bacteria get into the nodules, and the characteristics of symbiosis. Also, PGP tests including dissolved phosphorus, iron carrier, and IAA prudction charactersitics were carried to determined the effects of endophytic bacteria on plant growth and rhizobial informing. This research helps to rich species diversity of Qilian Mountains, discusses the mutual relationship between endophytic bacteria and root nodules, and also provides the basis to scientific using of some endogenous bacterial rhizobia and expansion research vision of rhizobia.

本课题以祁连山豆科植物的根瘤及其内生细菌为原材料，采用多相分类技术，明确其系统发育和分类地位，阐明多样性与海拔的关系，同时发掘新的根瘤内生菌种质资源。利用AFP标记技术进行回接试验，结合nif和nod基因研究，分析内生细菌进入根瘤的方式及与根瘤菌的关系，解析其共生特性，探讨根瘤内生细菌形成的初步机制。测定其溶磷、铁载体、产IAA及固氮特性，确定内生细菌对植物生长和根瘤形成的影响。该研究有助于丰富祁连山物种多样性，对于维持祁连山生态平衡和促进农业可持续发展有重要意义；探讨根瘤内生细菌与根瘤的相互关系，可为我们今后扩展根瘤菌研究视野、科学地利用某些根瘤内生菌提供依据。

为了丰富祁连山物种多样性，维持祁连山生态平衡和促进农业可持续发展，本课题以祁连山豆科植物的根瘤及其内生细菌为原材料，采用多相分类技术，发掘了新的根瘤内生菌资源，明确了其系统发育和分类地位，同时阐明了多样性与海拔的关系。结合共生与持家基因的研究，分析了内生细菌进入根瘤的方式及与根瘤菌的关系，解析了根瘤内生菌多样性的形成机制与其共生特性，探讨根瘤内生细菌形成的初步机制。测定了其溶磷、铁载体、产IAA及固氮特性，确定了内生细菌对植物生长和根瘤形成的影响。